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Changing 47 ohm resistors to a lower value?
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Changing 47 ohm resistors to a lower value?

by Rotary Rasp on Mon Jan 28, 2008 5:49 pm

Since these IR leds run at 1.5 volts, what is the reason for using 3 AA's? (4.5 volts).

Couldn't the 47 ohm resistor be replaced with a lower value to increase brightness without raising the source voltage?


Thanks
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by adafruit on Mon Jan 28, 2008 11:19 pm

because the Vce of the transistor is one of the major factors, thus a higher Vcc allows more breathing room...the base current into the transistor is already maxed out.

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